#9.5 Drilled Rubber Stopper (DRS)
The #9.5 Drilled Rubber Stopper (DRS) is a pure white gum laboratory stopper. The top diameter is 1 13/16", the bottom diameter is 1 1/2", and it has a 3/8" hole drilled in the center, the perfect size for an airlock.
This stopper fits most 2000 mL Erlenmeyer flasks.
The #9.5 rubber stopper is also available as a #9.5 solid rubber stopper.